Plug a new electric Nissan Leaf into a charging station, and it’s easy to feel good that the vehicle’s environmental and climate impacts may be small compared to all the cars on the road running on gasoline.

But driving an electric car could be worse for both the climate and public health if the electricity that runs it was generated at a coal-fired power plant. If that electricity came from solar or wind generators, then an electric vehicle is among the cleanest forms of transportation around.

Tailpipe exhaust from an old car. Some electric vehicles using electricity generated from coal-fired power plants could be worse for air pollution than gasoline-powered cars. Credit: JT/flickr

In fact, the environmental and human health costs of operating an electric vehicle using electricity generated from coal may be as much as 80 percent greater than driving a gasoline-powered vehicle, according to the study, conducted by a team of researchers at the University of Minnesota and published Monday in the Proceedings of the National Academy of Sciences.

The environmental health cost of driving an electric vehicle using electricity from solar or wind generators could be as much as 50 percent less than environmental and health toll of using gasoline.

“To have large improvements in the environmental health impacts of transportation relative to our current technology — gasoline — you really need to switch to electric vehicles, and that electricity needs to be clean, or radical improvements need to be made in fuel economy,” study co-author Julian Marshall, an associate professor of environmental engineering at the University of Minnesota, said.

Climate Central did a related analysis in 2012 and again in 2013, but only analyzed the greenhouse gas emissions impact. Here, the environmental findings are similar and these researchers have also shown there is a negative public health impact of coal-powered electric vehicles.

The researchers at the University of Minnesota investigated how the production and burning of 10 different gasoline alternatives affects costs and deaths associated with air pollution-related human health problems. Those alternatives, often cited as possible choices friendlier to the climate than gasoline, include diesel, compressed natural gas, corn grain ethanol, corn stover ethanol and electricity generated from a variety of renewable and fossil fuels.

Hundreds of thousands of people die from air pollution in the U.S. each year, some of which can be attributed to burning transportation fuels, Marshall said.

Vehicles running on electricity coming from coal-fired power plants ranked highest for both annual deaths and human health costs compared to gasoline, followed by vehicles running on electricity taken from an average electric grid operating today, which uses power generated from coal, natural gas, renewables and other sources.

Cars running on electricity coming from wind and solar ranked best overall, followed by electric vehicles using power from natural gas power plants and vehicles that are gasoline-electric hybrids.

“Any honest accounting of greenhouse gas mitigation strategies must account for co-benefits and consider the possibility of unintended consequences,” said Timothy Johnson, an associate professor in the Nicholas School of the Environment at Duke University. Johnson, who is unaffiliated with the study, added that any side effects to petroleum alternatives mustn’t be ignored.

“The emergence of alternative transportation energy resources has been interesting to watch, if for no other reason that it couples transportation energy resources with agriculture and power production,” he said.

Smog over Los Angeles. Credit: Robert S. Donovan/flickr

It’s important to understand the local environmental impacts of the production and consumption of these fuels, including increased air pollution from truck traffic going to ethanol refineries, he said.

“While these considerations go beyond the paper’s focus on air quality, the study reminds us that we need to widen our analytical boundaries if we are going to address greenhouse gas emissions sustainably,” he said.

Climate scientist Ken Caldeira of the Carnegie Institution for Science in Stanford, Calif., who is unaffiliated with the study, said he’d never seen a similar analysis, and it scoops a paper he and his team have been working on.

“Unfortunately, when a wire is connected to an electric vehicle at one end and a coal-fired power plant at the other end, the environmental consequences are worse than driving a normal gasoline-powered car,” Caldeira said via email.

“But electric vehicles are still good because they move us down a path toward a future near-zero emissions energy and transportation system,” he said. “Unfortunately, given the way electricity is generated in the U.S. today, the first steps down this path to lower pollution involves increases in pollution.”

Jim Parks, of the National Transportation Research Center at Oak Ridge National Laboratory in Tennessee, cautioned that the study is complex, and its conclusions should not necessarily be used as the basis for any choice of vehicle fuel.

Even electric vehicles using coal power might have an environmental benefit because they do not emit pollutants where they are driven, he said.

Once you take in the amount of pollution (from coal fired electricity plants) made to refine the oil that you later burn even coal fired power for electric cars is better than the status quo

Peter Campbell 5 years ago

That study seems to be an outlier. A few years ago a review paper of studies into this question found that the results ranged from the EV being only marginally worse than a similar vehicle using petrol to about 50% depending on the mix of inputs into the grid at the location of the study and a range of other assumptions and details.

However, the grid was getting greener till we had Abbott and presumably will return to the improving trajectory once he is gone. Meanwhile, buy greenpower for your EV. It will still be cheap to run, tax deductible too if you get it here: tinyurl.com/k8wlf6k

Bob_Wallace 5 years ago

All the previous studies I’ve seen have been CO2 emission comparisons. This study brings in other pollutants – soot for example.

Coal is nasty. A lot of the problems attributed to an EV burning coal-electricity is created at the mine and during coal transportation, not during the burning.

We need to make it clear to the public. There is a huge cost created by coal which is not folded into our electricity bill. In the US we pay between $140 billion and $242 billion every year in public health costs to cover the external costs of coal. Taxpayer money.

Coal-fired power stations cost the European Union up to €42.8 billion a year in health costs associated with coal-fired power stations. ‘The Unpaid Health Bill: How coal power plants make us sick’ — found that EU-wide impacts amount to more than 18,200 premature deaths, about 8,500 new cases of chronic bronchitis, and over four million lost working days each year.

The total costs are up to €54.7 billion annually when emissions from coal power plants in Croatia, Serbia and Turkey are included.

Agreed we need to get out of coal. Petroleum too. I advocate for EVs entirely because they offer a way to avoid both and run a substantial part of our transport needs on renewables. As a discretionary load, they offer further benefits for load management. Eg. get a signal to start car charging when there is an excess of wind or sun power available.

George 5 years ago

unfortunately, from what I can tell this study is yet another example of highly educated ignorance. If researchers like this had a clue about how the grid works and how EV’s are typically charged they could surely turn the whole thing on its head and come to the opposite conclusion: “Electric Vehicles Stand To Make Even Coal Burning Power Plants Cleaner Per Kilowatt Generated”. The bulk of electric car charging happens at night when off peak generation capacity normally goes to waste. By providing a much needed way to store the off peak electricity for daytime use, electric vehicles not only likely add very little additional pollution to grid production, they likely improve the overall efficiency and increase the profitability for utilities, which can now sell capacity that otherwise has gone to waste with the side benefit of potentially lowering utility costs for everyone. Estimates suggest that there is enough off peak waste every night to offset the addition of new vehicles for quite some time to come without burning any more coal or splitting any more atoms or running any additional water though dams.

Miles Harding 5 years ago

Cheers Bobby,

I’m off to move some funiture. The car charged overnight from a battery, charged by the sun the previous day! No coal involved in this production.

Merry Xmas, Bob, Peter and all

Bob_Wallace 5 years ago

Happy Holidays to you. I’m so looking forward to the lengthening of the day. Seems like there ought to be some sort of celebration for that….

Question for Oz – do you have higher wind output at night?

In the US we do. By charging EVs at night with wind we create a larger market for wind farms. That means profits for wind farms, more capacity built, and more capacity during peak hours. It’s a win-win.

Miles Harding 5 years ago

There certainly should be!. The opposite is true here in Aus. Maybe it’s the year to add another kW (of east facing panels, this time) before the sun returns to the northern hemisphere.

Bob_Wallace 5 years ago

My plan for the coming summer is to add one or two kW of panels on my roof and swing my ground mounted panels to the east. I’ve got trees that have grown and are now giving me partial shade in the middle of the winter.

I can now put up 2 kW for half of what my first 1.2 kW cost.

wmh 5 years ago

The culprit could very well be cars, however fueled.

Cars use an enormous amount of energy just to move the car itself, not the groceries. Cars abrogate an enormous amount of real estate in a city to their use – garages, parking lots, on street parking, the street common area which used to be used for children playing ( now locked away inside playing computer games).

Road accidents use up hospital beds, road building uses up resources, driving uses up people’s free time unproductively when they could be on the train reading a book or laptoping.

I ride a bike to get the groceries and also to get to work. I dont have to spend as much time at the gym, my garage is used for accomodation and my dead end street is used by children to play cricket.